Animals and neonatal treatment with MK-801
All our experimental procedures were carried out in rigorous accordance with the ”NOM-062-ZOO-1999” local regulation for the use and care of laboratory animals and the protocols authorized by the internal ethics committee (CICUAL) of our institution (CINVESTAV; Protocol number 0090-14), which mandate the minimization of suffering and the number of experimental animals used. These regulations and protocols are consistent with the ARRIVE 2.0 guidelines, the recommendations made by the British Journal of Pharmacology (Lilley et al., 2020), and the National Institutes of Health (US) guidelines for animal care.
Pregnant Wistar rats were supplied by our vivarium and given continuous veterinary care. The rats were housed in the following control conditions: an inverted light-dark cycle (12 h; the light was turned off at 10:00 h), a room temperature of 23 ± 1° C, and free access to food and water. The pups’ birth was designated as postnatal day 0 (P0), and animals were kept with their mothers until P21. The experimental procedures were performed in two cohorts of male animals ranging from 30 to 38 days old. Each experimental manipulation was carried out in at least three different litters. From P7 to P11, the animals received daily subcutaneous injections of either saline solution (SS, 0.9%) or MK-801 (0.2 mg/kg in a 2 mL/kg volume) (Griego et al., 2022; Márquez et al., 2023). The behavioral procedures were carried out between 10:00 and 16:00 h. The experimental animals were treated with SS or MK-801, following a single sequence of random assignments. The MK-801 was dissolved in isotonic SS. Animal suffering was minimized during and after the injections to reduce behavioral or neurophysiological alterations that might affect the experimental results. In addition, the assignment of animals to control and MK-801 groups was blind, to prevent any potential bias.